In medical specimen testing, purified water may be dispensed for various purposes. In certain clinical analyzer instruments used to test for the presence of an analyte in a biological fluid sample (otherwise referred to as “specimens”), it may be desirable to precisely meter water to be used in the process. For example, in some automated testing systems (e.g., clinical analyzer or immunoassay instruments), specimens contained in sample containers (such as test tubes, sample cups, vials, cuvettes, and the like) may be tested to determine a presence of a particular analyte, substance, or characteristic. As part of this testing process, precise metering of a process liquid (e.g., purified water) and/or control of a temperature of the process liquid may be desired in order to provide for testing accuracy.
For example, in some testing methods, such as the so-called “chase method,” a volume of specimen liquid is first aspirated and dispensed by a metering apparatus, and the dispensing of this specimen liquid is followed (chased) by dispensing a metered volume of a process liquid (e.g., purified water). In the chase method, the volume of dispensed process liquid may be greater than the volume of the specimen liquid that is dispensed. In the so-called “neat method,” a small amount of specimen liquid is aspirated and dispensed (on the order of less than about 10 μL). In the neat method, the process liquid itself (e.g., purified water) may be the vehicle (e.g., the liquid backing) that allows for the metering of the specimen liquid, even though the process liquid (e.g., purified water) may not itself dispensed in the neat method. However, for both methods, it should be understood that inaccurate metering and/or changes in the temperature of the process liquid may lead to inaccurate specimen testing results.
Accordingly, methods, systems, and apparatus that may improve aspiration and/or dispensing of a process liquid (e.g., purified water) or other liquids are desired.